Alan P. Bell, a Kinsey Institute researcher who helped conduct a pioneering large-scale study that countered the notion that homosexuals were maladjusted, died on May 13 in Bloomington, Ind., where he lived. He was 70.

The cause was a stroke, his wife, Shirley, said.

In 1968, Dr. Bell and a colleague, Martin S. Weinberg, began surveying nearly 1,000 gays in San Francisco to assess their mental health and to try to determine what, if anything, in their lives had influenced their sexual orientation.

It was the most ambitious study of male homosexuality ever attempted, said Martin B. Duberman, a history professor at the City University of New York who has written on gay issues. The resulting books, Homosexualities (1978) and Sexual Preference (1981), refuted a large number of previous studies that gay men were social misfits, Professor Duberman said.

The study found that homosexuals were as well adjusted and as satisfied in their relationships as heterosexuals. The researchers argued that there must be a biological basis for homosexual orientation, because they did not find that parental personalities or traumatic experiences played a role. That conclusion was greatly debated, with critics raising questions about methods.

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I expect the study to be condemned from both sides, by the radical gays for even looking into the subject and by the analysts who may say we're trying to paint a glowing picture of homosexuality, Dr. Bell said in 1981. But we reported what people say, and it's all very consistent.

Alan Paul Bell was born on Jan. 18, 1932, in Newark. He earned a bachelor's degree in philosophy from the University of the South and a master's from the General Theological Seminary. As an Episcopal minister, he helped found a parish in Denville, N.J., before earning a doctorate in counseling from Columbia University in 1964.

Dr. Bell became a research psychologist at the Alfred C. Kinsey Institute for Sex Research in 1967 and became a full professor at Indiana University in the early 1980's. He founded the university's Center for Human Growth, which provides low-cost counseling. He became professor emeritus in 1997 and established a large therapy practice.

His first marriage, to Lundie Lenoir, ended in divorce. In addition to his wife of 37 years, the former Shirley Levine, he is survived by a son, the violinist Joshua Bell of New York; three daughters, Terry Milazzo of Bow, N.H., Toby Gill of Indianapolis, and Rachel Bell of Chicago; a sister, Patricia Kirkwood of Montclair, N.J.; and four grandchildren.

Alan P. Bell, a research psychologist who led a groundbreaking Kinsey Institute study two decades ago suggesting that homosexuality has a biological basis, has died. He was 70.

Mr. Bell died of a stroke May 13 in a hospital in Bloomington, Ind.

A retired professor of counseling and educational psychology at Indiana University in Bloomington, Mr. Bell was a senior research psychologist for 14 years at the Alfred C. Kinsey Institute for Sex Research.